The invention relates to an electrophotographic process of preparing a microfilm and to a system therefor, and more particularly to a process of and a system for preparingg microphotographs by using electrophotographic microfilm in an electrophotographic process.
In addition to the microfilm used for preparing silver salt photographs, there is a microfilm adapted for use in electrophotography. The photosensitive film used in electrophotography comprises a photosensitive layer which is a thin film of organic photoconductive material coated on a film of polyester. Microphotographs are made by subjecting such film to the known electrophotographic steps of charging, exposing and developing. The resulting electrophotographic microfilm may be taken up on a suitable reel so that it may be stored as a recorded roll of film. Alternatively, it may be cut to suitable lengths, for example, lengths each providing a succession of 12 frames, and the cut film can be arranged on and affixed to a suitable transparent thin mount of transparent frame to provide a microfiche suitable for storage.
When subjecting electrophotographic microfilm to electrophotographic processings, either the units for charging, exposing and developing may be fixed, with the film moving across them, or the film may be held stationary while these units may be moved to be sequentially brought opposite the photosensitive surface to provide the respective processing steps. When the film is moved, the planarity of the film at the respective processing positions must be repeatedly reestablished each time the film is moved, which is inconvenient. Consequently, the latter method of maintaining the film stationary is preferred because it is only necessary to establish the planarity of the film once.
In the developing step, it is advantageous to employ a wet developing process in which the developing takes place by way of a developing solution, in view of its simplicity as compared with a dry developing process which needs a heat fixing step. When supplying developing solution to an exposed photosensitive surface, a liquid-tight developing chamber can be defined by the photosensitive surface and a vessel of developing solution located opposite thereto, with the developing solution being supplied into the interior of the chamber to contact the photosensitive surface. It would appear that when the film is placed in a horizontal position above the vessel, with the plane of the photosensitive surface facing down, the supply and drainage of the developing solution to and from the liquid-tight developing chamber defined therebetween would be facilitated. However, when the film is held in a horizontal position, with its photosensitive surface facing down, great difficulties are involved in conveying the film, because its photosensitive surface must be maintained clear of any conveying means. Consequently, it is advantageous to move the film in an upright position, in a vertical plane, and to hold it stationary in such position.